Many things can cause this.

Base on what I read, it doesn't sound serious enough to prevent you from driving. However, it's better to get it checked out and fixed.

At the link below, they talked about 2000 Accord, but the it might be similar to your CRV.

Read for yourself.
http://www.honda-tech.com/showthread.php?t=1485884

The P1259 (P1257, 58 and P1259) refer to Vtec System Malfunction. Oil pressure, or momentary pressure loss (low oil level) can cause this; as can a malfunctioning VTec control solenoid.