This is not the first time its happened. WHat is wrong with your networks? I keep missing things due to this issue. I am in downtown los angeles area code 213 . Zipcode 90012. PLEASE FIX IT. Texting is a really basic service. There are no excuses for it not to work right.
I am not seeing any reported outages in the area you have posted. Have you checked the coverage area on www.sprint.com/coverage? You may also want to turn your phone off and remove the battery (not available on iPhone) for a full minute and power back on. If this continues, you may want to call technical support and get this reported in.