When she does see you and comes out is she sluggish at all? Even just a little bit? Or at that point is she her regular self?
7 years old isn't really "old" in terms of the smaller breeds of goats, but so many things can affect their health that sometimes by the time they reach 7 or 8, it can seem like they are old. Also, deafness (or getting hard of hearing) wouldn't be that uncommon either.
Sometimes I have had a goat so sacked out I thought they were dead. I would call their name and get no response, so I would panic and go check on them, only to have them pop a lazy eye up and me and accuse me of disturbing a terrific dream of them dancing in a meadow somewhere chasing butterflies.
If it were my goat, and it was as unusual as it seems, keep an eye on the goat and if anything else seems off perhaps call a vet. Goats need regular deworming and routine health care like horses. If you have had a wacky winter like many of us have, it affects the life cycles of parasites, which are very different than horse parasites, and with the weather warming up now the parasites are active. She may not have a huge parasite load, but a higher than normal one can take its toll and make a goat seem like it has less energy.
If you would be interested in some really good goat websites that address many heath issues or concerns, or general info on anything goats, PM me and I would be glad to send them to you.