without seeing a pic it sounds like warping, where the print is pulling free from the bed so it doesnt get printed correctly
if you get a sheet of buildtak and put it on your print bed (
www.buildtak.com) it wont peel up again I promiss
if you put the buildtak on you will need to reset your z axis (home location)
you can also try putting some purple glue stick on the print bed or spraying a coat of Aquanet Superhold on it works also