Maybe he was GOING to text you back, but he started looking up anniversary presents EARLY, like good ones, and his text function got all jammed up, but the internet, thankfully, was still going strong, then something totally crazy happened (he'll tell you about it), and...
I heard it had something to do with solar flares delaying the delivery of text messages. the ambient electromagnetic radiation exceeded his phones ability to recieve text messages (which is sent and recieved on one radio frequency), but not the internet - which is sent and received on a separate frequency.
In the end, he may have even replied already, except the solar flares are preventing delivery in a timely fashion.