Starters are strange beasts

I have been running my sourdough starter for about 18 months.  Initially I fed it 100% wholemeal rye flour.  I liked the way it didn't go stringy and was easy to measure out.  It always smelt quite acetic when done, but I could change that by feeding it with wheat flour at lower hydrations prior to using it in a bake.  

Then towards the end of last year my dough stopped rising much and baking decent loaves became difficult (difficult to judge when the dough was done, easy to over-proof), so I left the starter in the fridge for a few months.

Recently I revived it, carefully scraping off the black mould and digging down to the pale pasty substance that had collected at the bottom of the pot and using that.  But I fed it 50:50 wholemeal wheat:plain white wheat flour (100% hydration as before).  From the off it smelt different and after a few feeds baked a decent loaf - the rise was back (not amazing, but at least there was some) and the flavour quite different in the finished loaf - only a very slight acetic hint but quite a pronounced sour tang.  Previously, even when it was working and I fed it just wheat for a few feeds it wasn't quite like this, it is definitely a different beast now.

I think it must have had time to reflect on things when in the fridge and has just bucked its ideas up generally.