Mortgage payment dates that change each month?

My mortgage leaves my account at the end of every month on different dates, I was just wondering if this is unusual at all. A lender that our mortgage was previously with took our payment at the beginning of the month on the same date every month, which I found easier than what I have for the last few years.
I find it seems like the mortgage comes round sooner some months ie if there are fewer days in the month we find it a little tougher to budget in time..
Is this the norm, I am just wondering if they should be taking our monthly payment in this way, I will give you an example..one month could be the 28th the next could be the 30th followed by 31st etc..if there is a bank holiday for example they would take their payment on the 28th of the month, sometimes feels like they are suiting themselves and their payment is never set to collect on a weekend which if my memory serves me correctly would just mean they take it on the next banking day but not my mortgage provider they get in with it well before hand.. Can you tell if this is the same for others or is this just the way my mortgage provider does it,
Thanks
Graft..

im with Ulster bank and our mortgage comes out on the 27th of every month..if the 27th is a sat or sun it comes out that monday if the 27th was a bank hol monday it comes out that tuesday after.. never before.

I thought that DD agreements normally stated "on or after <some specific day of the month>" - the variability arising due to weekends, bank/public hols etc.?

yes that is my understanding of when direct debits are paid too, every other direct debit that I have or have ever had went on the same day every month or next banking day after the weekend or bank holiday etc.
I have looked back on my direct debit dates to my mortgage provider and there is actually one month where it went on the 25th of the month due to there being a shorter month and a weekend,it varies between the 25th to 31st of any month depending on how the month falls so their thinking is get the payment sooner not later which leaves us some months having to budget differently..
I never really thought about it too hard, I will have to contact my bank and ask them about the direct debit agreement that was initially put in place as I think there is too much of a variable, everyone else that I know would have more time to pay their direct debit due to a weekend or a bank holiday etc, we would have less, I feel we should just have the same day every month regardless of holidays or weekends etc..

Hi Graftgirl,

sounds like your DD is for the last working day of the month. Usually they're for the first working day, but it's at least easy to work out in advance which day it will be so you can budget accordingly.