Brakes on

[A55]

I have a MR2 convertible that I rarely use, but when my Alfa was off the road I took it to work. About a mile before I got to work the brakes started binding, I had just come off the motorway. By the time I got to work they were holding noticeably. I parked the car planning to call breakdown when my shift was over but 30 minutes later the car was stood in the middle of the car park although the handbrake was on. I drove it home with no issues. I had brakes and callipers done in March. Been meaning to take it back to the garage that done the brakes.

Again thoughts on what might be wrong anyone?