Tell me why I saw a tinder notification on my boyfriend's phone?

I was snuggling with him and my head was on his chest while he was on his phone playing a game. I looked up and saw a tinder notification and he must have noticed I saw and he swiped it away real fast.

Also he had his phone connected to a bluetooth speaker because we were watching YouTube earlier before he played his game and when he went to the bathroom he took his phone with him. I heard a camera sound come through the speaker when he was in the bathroom. Uh huh yeah I'm mad.

I'm not saying anything yet. I'm keeping this in my back pocket for now.