I was away on a course, not just socialising, and very busy physically and mentally from 9-6pm. Emotionally exhausted as well by the work, but still with every intention of texting her. I would not have let the day go without texting. No, certainly not unreasonable for her to look for a message. It was her comment that I found concerning, the 'had to'. No one should be manipulating anyone into texting.
Perhaps my response to your reply torturedsoul has clarified my own thoughts on this.