You can log it. You should log it.
Five aircraft category ratings may be placed on your pilot certificate; you may log time in any of them. They are Airplane, Rotorcraft, Glider, Lighter-than-air, Powered-lift.
Remember that the only time you must log is that time used to show recency of flight experience, or time credited toward any certificate, rating, or operating privilege. You don't need to log any other flying, but you really should.
To meet the recency of experience requirements of 14 CFR 61.57(a)(1)(ii), you must log the landings in the same category and class. If you want to be current in a glider, then log your glider time. If you want to be current in an airplane, then log the airplane time.
I suspect that's not so much what you're asking, than how the time will look in your logbook. In other words, I'm guessing you want to know if it looks bad to have glider time in your logs...weather or not it appears that you're padding your logbook. Is that right?
In short, no, there's absolutely nothing wrong with having glider time in your logbook. I do. It shows diverse experience, and there are things you'll learn flying a sailplane that you won't learn anywhere else...these things enhance your overall skill and knowledge base, and make you a better pilot (if you let them).
Log the time. You need to do so to show recency of flight experience, anyway. All it does is show that you've put forth greater effort at being a better pilot, and for that, you're to be commended.