Don't worry about it, I use lenses older than yours, ( my oldest is a 1936 Voigtlander skoper atached to a baby bessa, a folder of that era), in fsct the newest lens I have is on a 1959 Rolleicord)and I have by accident touched the lenses, it hapens to the most careful user, all I havev ever done in 60 years is to breath on the lens and clean, these days I use microfibre lens cloths, in the old days I would use lens tissues if I had any, if I didn't I would use a tie if wearing one, or my shirt, in my old days it was the right way to clean a lens, many a newspaper or pro photographer would clean there lenses that way, I have yet to damage any lens, or see any lens damaged by carefully cleaning a lens with tissue/lens cloth/tie Ect and breath, I have never used lens cleaning liqued, and never will, after all, all it is is very expensive alcohal, so if you are that worried get a tiny drom of whisky/brandy/ any sprit will do, but I say breatth on the lens and clean the mist off with your Micro fibre lens cloth any time, all will be fine. all I would add is to get a lens brush. either a blower type or the ''lipstick'' type and dust the lens first to remove any fine dust befor micro fibre and breath cleaning