Yes, there were changes to entitlements for MIS from January (apart from the 12 month MARP requirement which Steiner mentions above, which applies to new claims from mid-June).
The minimum contribution which was €24 pw last year is now €30 pw for a single person or €35 for a couple.
If the interest rate has changed on your mortgage, or the amount of interest v capital you're paying has changed since last year, that may have affected your entitlement, as only the interest portion can be considered.
You can ask for a calculation sheet from the SWA officer to show where the final entitlement came from.