Baby mimics?

I had a thought for my campaign and wanted to run it by smarter people.

My party fights a decently strong monster. They have to work hard and smart to defeat it. Afterwards they loot the lair and find an old worn box with 400 gold in it. In reality the box is an old mimic on it's last legs. Half the gold is baby mimic in larvae stage. They look and feel like gold coins.

The party goes to town and starts spending gold. Each transaction the DM rolls some dice to see how many babies are spent instead of real gold.

At some point in game time they start to wake up/hatch and attacking people. The residents somehow link this back to the party (maybe they all wake/hatch at the same time so they may still be in a town). Now the party has to deal with whatever the game is and their suffering reputation.

Thoughts?