AITA - Using my brother’s toothbrush for ~6 months.

My brother and I live together, and for the past 6 months I’ve been using his toothbrush every morning because I genuinely didn’t see what the big deal was.
It’s just a toothbrush. We’re brothers, we share food, drinks, towels sometimes, etc. I always rinse it properly afterwards and put it back exactly where I found it.
He only found out yesterday and absolutely lost it. He says it’s “disgusting” and that I’ve been secretly using his toothbrush for months.
I honestly think he’s massively overreacting. If anything, I think he’s making it weird.

AITA?