I don't think you're being unreasonable It's common courtesy and not at all unreasonable to expect to be treated with common courtesy when acting in a like manner.

I think you have to change your settings to have a read receipt returned to you when your PM's are read. I need to do the same, come to think of it I would like to know when my PMs are read too, since I hate having people contact me about products and then drop off the face of the earth. I guess their mommas never taught them manners.