We present a preliminary study on how followers and non-followers of a popular CEO respond differently to a public apology by the CEO in Twitter. Sentiment analysis tool was used to measure the effect of the apology. We find that CEO's apology had clear benefits in this case. As expected, it was more effective to followers than non-followers. However, followers showed a higher degree of change in both positive and negative sentiments. We also find that negative sentiments have stronger dynamics than positive sentiments, in terms of the degree of change. We provide insights on the potential for efficient crisis communication in online social media and we discuss future research agenda.