LTE problems

Okay so I am using the iPhone five on AT&T, When I am in a LTE area, sometimes it will drop the LTE and default to 4G, Meanwhile my second phone I carry which is an android phone that is LTE will not drop the signal ever. To get the iPhone to switch back to LTE I have to toggle airplane mode on and off then it will work fine. If I do nothing and leave the particular area to go to a much stronger LTE signal area It can take quite a while before it will switch to LTE in the strong signal area. I've done several restores, installed minimal apps, so I don't know if it's a software issue or not. My android phone has no issues with switching from LTE to 4G, it's flawless, so the iPhone has me concerned, should I exchange it for a new one or is this normal for the iPhone, I really hate to give up my iPhone for a refurbished one at the Apple Store.