I don't know, I've never had that problem with my hubby and he's the only one I've ever been sexually intimate with, so I don't have any other experiences to compare. He's pretty quick after I've had mine as he's always the gentleman and he waits until I've climaxed at least once, before he does his thing. But if we pull a quickie, meaning, I'm just wanting him to enjoy himself and not worry about me, it doesn't take but a minute or two. I have to admit that the occasional times when he's wanting to keep going for a while, and hold off climaxing, I start to get pretty sore and it ends up really uncomfortable so I honestly prefer the faster route. If I were you, I would just ask him if there's anything else he would like to try. Maybe he's embarassed but has some type of new position he might be interested in. Or, maybe he's not comfortable with the whole sex thing, maybe he has some unresolved issues. I don't know. But I wouldn't worry about the amount of time he's taking, unless you aren't enjoying it at all. Sometimes, all it can take is one time of taking longer to climax to get yourself stressed out worrying that it's going to happen again, basically meaning, that he may be psyching himself out negatively before sex even begins which results in delayed orgasm. The mind is a very powerful thing! Another thing is, is he on any medications that could be tampering with his libido? Some meds can just about destroy sexual urges, making climax next to impossible. I myself was on a med at one point that did that. I ended up discussing it with my doctor so that he could change my prescription. It helped tremendously.
Get him in the mood. Give him some good visual. A good BJ to get him going is always bonus. Foreplay is key here...if you get him going halfway there, he'll take half as long. However...sometimes taking awhile can be a blessing. Lube is choice! (man, I'm saying that a lot today!)