It is interesting to note that in the latest cash call by Barclays, Temasek only contributed a measly 200 million pounds. I think This has more to do with a diluation issue than having a real interest in buying the share at a 9% discount to the stock price as of Tuesday.
So, if we apply Buffet's definition of a good stock (of buying more when the price drops), then indeed Temasek's action may have the following implications:
a. That they may have paid too much last summer
b. That there may be more write-downs for Barclays and a further cash call