Do a proper safelight test as fotch suggests. Both Kodak and Ilford have good instructions.
Check other things too. Light leaks from the enlarger, enlarging light reflecting off other surfaces in the darkroom (including you). Light from outside the darkroom etc.
If it is the safelight, remember filters fade with time/use so how old or used is the filter? What wattage is the bulb? Even with a proper safelight setup, most paper manufacturers recommend keeping it at least 4 feet from the easel. Indirect light is usually preferable to direct light. Etc. All these things factors (including the type of paper) can influence the safe time.