Make sure that that it is actually a pump and not something more serious. Before I injured my back I would get a "pump" feeling while doing those lifts and the underlying issue was the start of disc degeneration in my lumbar region. I always fought through it though and feeling subsided after about an hour, leaving me no worse for wear until I injured it.
It's hard to check, but if you have a good chiro that you know of it wouldn't hurt to get checked out.
Class I Total @ 198: 525/335/600 (1460)
"No citizen has the right to be an amateur in the matter of physical training.... What a disgrace it is for a man to grow old without ever seeing the beauty and strength of which his body is capable."