Generally speaking, you probably could go up half a gauge without having to file the nut, right? My Jazz came with 45-100 and I want to go up to 50-105. Having the nut filed by a pro around here means you give up your bass for a week, minimum.
If you use a d-tuner or alternate tunings you may want to go the extra step and have the nut work done. If you don't change tunings, then you should be ok. Typically the gauges are 40-100 (light) or 45-105 (medium) with all sorts of custom variations depending on the brand. That said, moving up by one gauge should not require filing the nut. A little graphite or nut sauce wouldn't hurt to be on the safe side and you will need to adjust the intonation at the bridge.
If you really need to, all you have to do is put the new string on (loosely - like an octave low) and take a little square of sandpaper (fine) and use the string as a little size-guide. Slide the sandpaper back and forth in the slot with the paper wrapped once around the string.
Should take 15 seconds or less. as long as you only sand the width, and don't go any deeper, you should be fine.