If a person you were once an acquaintance with and over the years, other than random 'hi' here and there, there hasn't been any kind of communication and they suddenly drop a "I missed you" text, isn't that weird?
I also don't do well with conversations without context. Since you aren't an ex/friend, missed me for what?
Had this been someone I was once close with, I still would understand, but it was so unexpected, I reacted with "lol what?" I kinda feel bad about my reaction tho.