Musket
Certainly, elastic limit could be a factor if this is reached.

Elastic limit is a notional one in all metals, permanent stretch happens with increasing value as the string is tensioned. And cold flow has time and tension dimensions. At the tensions put on strings, elongation is happening immediately and with time. The amounts are going to be small in percentage terms but in musical terms it is noticeable to all but beginners. The excessive plucking after new strings is going to add to it, and teasing out whether the effect is from the guitar, the nut, bridge, machine head, fold of the string round the post, kinks anywhere or pegs - or this mythically "absolute/binary" elastic limit is impossible.

When the strings are new the crystal structure of the metal is "as manufactured". After putting on the guitar and tensioning them it will be modified, slightly. With time the crystals will have slipped past in places. This is another way of describing cold flow but the change is permanent and is heard as a "tired string". cold flow never stops while the strings are in tension, its value will depend on the brand - hence the reputation/price of some brands. And is not metal fatigue just another manifestation of the same process? Vibration causing failure - and increasing evidence as it nears? Music - vibration: spot the link.

cold flow can be demonstrated very easily in a metal that exhibits a lot (ie ductile metals). e.g. Solder wire. If you unfold a length from the reel and place the reel at the edge of a desk, the wire sticking out in thin air. It stays there. Come back tomorrow - where is it now? In the days of tin/lead it would be vertical, and even with modern RoHS compliant tin/antimony solder wire it falls overnight.

I have known several guitarist who hate others using their instrument, citing the acid in sweat that they lovingly don't have! (as much of presumeably). Their solutions are "not with mine you don't", dry cloth and "Fast Fret" et al.