Brake Problem

A bit scary - having been out for a ride yesterday I wheeled the bike out of the garage this morning to find the brake lever had very little pressure, but pads were dragging a little. A couple of pumps brought the pressure back.
There's no sign of fluid loss from lever, calipers or lines, and the level in the reservoir is fine. I'm going to take off and inspect calipers but any thoughts about what the problem could be are very welcome.

 

Thanks - I gave them a good spray and clean with brake cleaner a few weeks ago, giving them a good going over again. Maybe got some grit in there, roads are still filthy.......

 

Cheers

 

Thanks - Lever feels solid after (another) clean, but will keep an eye on it.