There is no particular safety aspect to this other than the ability to loose power assist. There could be problems in the future in the hydraulic system if the P/S fluid were to co-mingle in that system for long periods. Hydro-carbon lubricants don't do well for the seals in mineral oil bassed hydralic systems.
There is no particular hurry about this as you obviously haven't been adding much oil. The hurry right now is just in indentifying your noise. If fluid fixes it, just tell your technician at your next service.