Bayern now have a goal difference of plus 15 after only five games of the season, and with Mario Gomez taking his tally to seven for the season, it looks like there is no stopping the record German champions.
However, Rummenigge was hasten to point out his side had only won three points.
"It was a great result, but we would be well advised to be very respectful with our opponents," he said.
"We should not get arrogant or carried away.
"We are going to be put to much sterner tests in the coming weeks."
However, like many of the 69,000 fans inside the Allianz Arena, he was pleased to see Franck Ribery back to his best form.
"That is the Ribery that we love," he said.
And the Frenchman explained the secret to his return to form, taking a swipe at Jupp Heynckes' predecessor on the Bayern bench Louis van Gaal.
"I am the old me again," he told reporters. "I am feeling good this season, also with the coach Jupp Heynckes.
"I have not had this feeling for two years now. I was tired and wasn't enjoying myself.
"Now things are better."
Better also for Bayern, who travel to face Villarreal in the Champions League on Wednesday in a very positive frame of mind.