I Have Occasional Problems Finding The Correct Word. At Dinner

I have occasional problems finding the correct word. At dinner tonight I couldn't think of the word for a specific vegetable. This has been happening recently possibly once a week About six years ago it started with occasionally not remembering a name. Very recently when reading I find myself reading a word wrongly. I am a 71 year old woman taking steroids for polymialgia for the past 18 months. Is this the possible onset of some form of dementia?