Hello. Thank you for coming to JustAnswer with your question, and welcome.
How old is your wife; and does she have any other health conditions or high blood pressure?
One extra dose will not hurt her. She may notice a slight increase in heart rate and/or blood pressure but this would return to normal by tomorrow. Most likely she will not notice any effects at all. She would have to take an extra dose for several days for it to be a problem.
If her doctor is still adjusting her dose, she would want to let him know however. Especially if she is due for TSH testing soon.