One larvae in my room after years

A year or three ago I had several carpet beetle larvae in my room. I cleaned everything, threw away my mattress and had an exterminator come to spray down my entire room. I haven't seen any since then, just one larvae in my house (several floors) every few months. I hadn't seen one in my room since the exterminator, but now I've found one under my mattress again. I vaccuum cleaned everything, washed my sheets (that's how I found it) and sprayed some pest control for crawling insects under my bed. I'm a rather anxious person, should I start worrying about this?