What happened to me? Wrists popping

For a year, I've been doing forearm wrist curls with hex weights (15lb).  Also doing reverse curls.  I stopped doing this for about a month.  I started back.... popping like crazy, like a old rusty door.  I try different angles, but still the popping.  Would this be normal after stopping for about a month?  Can anyone shed some light here for me?